Work vehicles, such as tractors, combines, and cotton harvesters, typically include or are coupled to various rotatably driven mechanisms for performing various functions. Such attachments typically require lubrication to facilitate their operation by reducing friction and wear of the various parts and components of such attachments.
For instance, a cotton harvester is provided with a number of harvesting units mounted, typically, at the front end of the harvester. Each harvesting unit has a rotatable harvesting mechanism which has individual lubricant or lubricant fittings to supply lubricant to the various picker bars, spindles, cam followers and drive shafts extending through the harvester unit. A drive gear arrangement located in the top of the harvester unit transmits power from a drive shaft to the drum and spindles. Each of these components require lubrication to operate properly and efficiently. Modern cotton harvesters can have as many as eight (8) row harvesting units mounted on the cotton harvester with each requiring lubrication as described above.
Several systems have been developed to provide lubricant to such attachments as described in U.S. Pat. No. 4,769,978 (issued to Reichen, et al.) which discloses a system requiring a pump to move lubricant from a reservoir to cotton harvesting drums and a separate additional pump for filling the reservoir with lubricant as the lubricant is used. Another approach is disclosed in U.S. Pat. No. 5,099,955 (assigned to the assignee of the present invention) which uses a single pump to move lubricant from a reservoir on an attachment to the cotton harvesting drums and it uses the same pump to fill the reservoir on the attachment from a source of lubricant, with the flow at the same rate in both directions. Filling the lubricant reservoir at the same rate of flow at which the lubricant is used by the attachment takes more time than desired by the operator. Using an additional pump is expensive and troublesome since a separate power supply is needed to operate the second pump. This latter system utilizes a plurality of valves to affect the directional change of the lubricant flow. The two systems described require multiple valves or multiple pumps operating at the same flow rates to move the lubricant as needed.
Thus, there remains a need to provide a lubrication system that can utilize a single pump for moving lubricant from a source of lubricant to fill a reservoir and to use the same pump to move lubricant from the reservoir to an attachment using such lubricant. There is also a need for providing a variation in the flow rates when the system is in the lubrication using mode, i.e., slow verses the lubrication fill mode, i.e., fast. It would also be advantageous to affect such transition between a lubrication mode to a fill mode with a minimum of valves.